A signal path provides a signal. A signal path has a propagation delay, which adds delay to a signal as it propagates through the signal path. The circuits of the signal path may have a power supply sensitivity. That is, as the power of the power supply varies, the propagation delay of the signal path may change, for example, when power decreases, the propagation delay typically increases through the signal path, when the power increases, the propagation delay decreases through the signal path.
Understanding that the propagation delay may change due to power supply sensitivity, a system including the signal path is designed with timing margins so that the system can operate correctly despite the variation in propagation delay. Designing in the margin to accommodate power supply sensitivity of the signal path circuits may reduce overall performance of a system including the signal path. In some cases, the power supply variation may be dramatic enough that the timing margin that is designed into the system is not sufficient to manage the variation, causing the system to operate poorly, or in a worse case, operate improperly.
In other systems, a power supply regulation circuit may be included to regulate the power supply, decreasing the power supply variation seen by the circuits of the signal path. Although a power supply regulated system has some resistance to power supply variation and the impact on propagation delay, the power supply may nonetheless decrease below a minimum operating level of the power regulation circuit, resulting in the circuit being unable to provide the regulated voltage to the circuits of the signal path causing the propagation delay of the signal path to change.